ON THE PHYSIOLOGICAL ACTION OF MEDICINES. 83 
ward afford additional confirmation of the views I have already advanced, 
and, with the facts that have been published, will, I trust, constitute a sufficient 
amount of evidence to firmly establish the truth of the law in question. The 
experiments I have now to bring forward have been performed with the 
tartrate of antimony, the salts of palladium and platinum, and with the chloric, 
hydrochloric, bromic and iodic acids. 
Tartrate of Antimony.—This substance when injected into the veins gives 
rise to exactly the same phenomena as would the arsenic or phosphoric acids, 
and which have been detailed in the last report. The quantity required to 
cause death was about a drachm of the salt. 
Chloride of Palladium—This salt is very poisonous, for when introduced 
into the veins it possesses the power of arresting the action of the heart, in 
smaller doses than any other substance I have experimented with. On inject- 
ing half a grain, dissolved in half an ounce of water, into the jugular of a dog, 
the action of the heart became rather fluttering after a few seconds, and then 
slower ; there was no expression of pain. On injecting a grain of the salt, the 
action of the heart was arrested in about 12". The respiration is often sus- 
pended for a minute or two, and then recommences, continues regularly for 
about a minute, and is again suspended. I have observed this to recur five 
times after the injection of two doses of a quarter of a grain each ; the animal 
lay on its side without the slightest expression of pain, although perfectly 
sensible; there were no convulsions: after death the heart was found quite 
still, the blood in the left cavities of a dirty scarlet, showing that the heart 
had not been arrested from asphyxia; it coagulated slowly; the lungs were 
almost white and anzemic. On injecting a solution containing half a grain 
into the arterial system, violent spasm was immediately produced: the 
pressure rapidly increased from 5 to 12 inches, as indicated by the hemady- 
namometer* ; respiration continued at intervals, and the pressure in the 
arterial system gradually fell, but was still at six inches four minutes and 
a half after all regular respiratory movements had ceased. The salts of pla- 
tinum give rise to precisely similar pheenomena when injected into the arteries 
and veins; they do not appear to be so poisonous as those of palladium, 
as it requires three or four grains to be injected into the vein before the action 
of the heart is arrested. Osmium and iridium, the other members of this 
isomorphous group, have not been experimented with on account of their 
great rarity. 
I have only now to notice the phenomena that are produced by the well- 
known isomorphous group—iodine, chlorine and bromine. The forms under 
which these substances have been used are as iodic, bromic, chloric and 
hydrochloric acids. I shall only allude to the effects that have been ob- 
served after the introduction of the iodie acid into the veins and arteries, 
as the acids of chlorine aud bromine give rise to effects perfectly analogous. 
_Todic acid and the substances that are related to it present an analogy with 
the salts of silver and soda in their action on the animal economy; they are 
however perfectly distinct in one or two particulars, in which also they closely 
_ agree amongst themselves, 
_. When injected into the veins, iodic acid evidently exerts an influence on 
_ the passage of the blood through the lungs: immediately after the injection 
_ of a solution containing 10 grains of the acid into the veins, the pressure in 
_ the arteries becomes lowered. In a short time we have most unequivocal 
roofs of its action on the lungs, by the escape of a quantity of frothy fluid 
m the air-passages, which soon causes the death of the animal by asphyxia. 
; oo The pressure in the arterial system is given in inches of mercury, as ascertained by the 
dynamometer. 
G2 
